1. Field of the Invention
The invention relates to a method for assigning individual phase conductors at one point to those at at least one further point in a polyphase energy distribution network, in particular in a three-phase network, in the case of mains operation, and to a corresponding device. Such a point can be located at any given point in the energy distribution network, however in any event the main connection points of consumers and also the distribution stations, such as transformer stations, mains distribution cabinets and the like are of interest.
2. Prior Art
Systems with three or four conductors are often used for three-phase alternating current transmission in electrical energy distribution networks, in particular in medium-voltage or low-voltage networks. When said networks are put into operation or expanded, attention is often only paid to a uniform phase sequence at the three-phase terminals of the households, for example to a sequence of the phase differences rising or falling by consecutive 120° cycles in a system with four conductors or between the line-to-line voltages in a system with three conductors.
The result of this practice is that an assignment between the individual phase conductors of a distribution station, such as a transformer station, and the phase conductors at the consumers is not known. In other words it is not known which phase conductor at the consumer corresponds to which phase conductor in the distribution station.
With the increasing decentralization of energy generation, by private photovoltaic systems or small combined heat and power systems in private households for example, the usage of the electric energy distribution networks is also changing: from a central power distribution—from one or more transformer stations to the consumer—to an at least at times decentralized power distribution—such as from one household to other households or from a number of private energy generators to the transformer station or into the medium-voltage network.
In order to be able to guarantee the monitoring and control of the voltage quality as well as the monitoring of the power distribution in such decentralized energy distribution networks, a unique assignment of one or more phase conductors at a consumer terminal to a specific phase conductor of a phase of the energy distribution network is required, also in the event of a change in the structure of the energy distribution network.
Employing network expansion plans or installation plans for this purpose is often not sufficient since said plans are incomplete or cannot correspond to the actual energy distribution network.
In accordance with DE 196 21 543 A1 it is known that a load can be connected for a defined period of time with a specific size to a network phase of the energy supply network and, on the basis of this upwards or downwards change in the load, the connected phase in the network can be identified. This has the disadvantage that, not only does an additional device have to be provided for this purpose but that this imposes a load on the energy supply network. With this method only one network phase can ever be checked and assigned.
EP 0 961 125 A2 proposes carrying out the phase identification of medium-voltage cables in a state short-circuited to ground, and doing this by injecting a tone frequency into the line to be identified. The disadvantage of this is that operation of the network must be interrupted to perform the identification. With this method too only one network phase after the other can ever be checked and assigned.